Save and restore from power off

src/hal/hal_esp32.c

@@ -75,6 +75,7 @@ static spi_transaction_t spi_transaction;
 static SemaphoreHandle_t mutex;
 static esp_timer_handle_t timer;
 static int64_t time_offset;
+static int32_t initial_time_offset;
 static int64_t next_alarm;
 static volatile bool run_background_task;
 static volatile wait_kind_e current_wait_kind;
@@ -306,11 +307,25 @@ void init_timer(void)
 
     struct timeval now;
     gettimeofday(&now, NULL);
-    time_offset = (int64_t)now.tv_sec * 1000000;
+    time_offset += (int64_t)now.tv_sec * 1000000;
+    initial_time_offset = 0;
 
     ESP_LOGI(TAG, "Timer initialized");
 }
 
+uint32_t hal_esp32_get_time(void)
+{
+    struct timeval now;
+    gettimeofday(&now, NULL);
+    return now.tv_sec + initial_time_offset;
+}
+
+void hal_esp32_set_time(uint32_t time_val)
+{
+    initial_time_offset = time_val;
+    time_offset = (int64_t)time_val * 1000000;
+}
+
 void set_next_alarm(int64_t time)
 {
     next_alarm = time;

src/hal/hal_esp32.h

@@ -35,6 +35,26 @@ void hal_esp32_set_rssi_cal(int8_t rssi_cal);
 
 TickType_t hal_esp32_get_timer_duration(void);
 
+/**
+ * Gets the time.
+ * 
+ * The time is relative to boot time of the
+ * run when the device joined the TTN network.
+ * 
+ * @return time (in seconds)
+ */
+uint32_t hal_esp32_get_time(void);
+
+/**
+ * Sets the time.
+ * 
+ * The time is relative to boot time of the
+ * run when the device joined the TTN network.
+ * 
+ * @param time_val time (in seconds)
+ */
+void hal_esp32_set_time(uint32_t time_val);
+
 
 #ifdef __cplusplus
 }

src/ttn.c

@@ -18,6 +18,7 @@
 #include "lmic/lmic.h"
 #include "ttn_logging.h"
 #include "ttn_provisioning.h"
+#include "ttn_nvs.h"
 #include "ttn_rtc.h"
 
 #define TAG "ttn"
@@ -236,6 +237,29 @@ bool ttn_resume_after_deep_sleep(void)
     return true;
 }
 
+bool ttn_resume_after_power_off(int off_duration)
+{
+    if (!ttn_provisioning_have_keys())
+    {
+        if (!ttn_provisioning_restore_keys(false))
+            return false;
+    }
+
+    if (!ttn_provisioning_have_keys())
+    {
+        ESP_LOGW(TAG, "DevEUI, AppEUI/JoinEUI and/or AppKey have not been provided");
+        return false;
+    }
+
+    start();
+
+    if (!ttn_nvs_restore(off_duration))
+        return false;
+
+    has_joined = true;
+    return true;
+}
+
 // Called immediately before sending join request message
 void config_rf_params(void)
 {
@@ -340,6 +364,11 @@ void ttn_prepare_for_deep_sleep(void)
     stop();
 }
 
+void ttn_prepare_for_power_off(void)
+{
+    ttn_nvs_save();
+    stop();
+}
 
 void ttn_wait_for_idle(void)
 {

src/ttn_nvs.c

@@ -0,0 +1,123 @@
+/*******************************************************************************
+ *
+ * ttn-esp32 - The Things Network device library for ESP-IDF / SX127x
+ *
+ * Copyright (c) 2018-2021 Manuel Bleichenbacher
+ *
+ * Licensed under MIT License
+ * https://opensource.org/licenses/MIT
+ *
+ * Functions for storing and retrieving TTN communication state from NVS.
+ *******************************************************************************/
+
+#include "esp_log.h"
+#include "esp_system.h"
+#include "hal/hal_esp32.h"
+#include "lmic/lmic.h"
+#include "nvs_flash.h"
+#include "ttn_rtc.h"
+#include <string.h>
+
+#define LMIC_OFFSET(field) __builtin_offsetof(struct lmic_t, field)
+#define LMIC_DIST(field1, field2) (LMIC_OFFSET(field2) - LMIC_OFFSET(field1))
+
+#define TAG "ttn_nvs"
+#define NVS_FLASH_PARTITION "ttn"
+#define NVS_FLASH_KEY_CHUNK_1 "chunk1"
+#define NVS_FLASH_KEY_CHUNK_2 "chunk2"
+#define NVS_FLASH_KEY_CHUNK_3 "chunk3"
+#define NVS_FLASH_KEY_TIME "time"
+
+void ttn_nvs_save()
+{
+    nvs_handle handle = 0;
+    esp_err_t res = nvs_open(NVS_FLASH_PARTITION, NVS_READWRITE, &handle);
+    if (res != ESP_OK)
+        goto done;
+
+    // Save LMIC struct except client, osjob, pendTxData and frame
+    size_t len1 = LMIC_DIST(radio, pendTxData);
+    res = nvs_set_blob(handle, NVS_FLASH_KEY_CHUNK_1, &LMIC.radio, len1);
+    if (res != ESP_OK)
+        goto done;
+
+    size_t len2 = LMIC_DIST(pendTxData, frame) - MAX_LEN_PAYLOAD;
+    res = nvs_set_blob(handle, NVS_FLASH_KEY_CHUNK_2, (u1_t *)&LMIC.pendTxData + MAX_LEN_PAYLOAD, len2);
+    if (res != ESP_OK)
+        goto done;
+
+    size_t len3 = sizeof(struct lmic_t) - LMIC_OFFSET(frame) - MAX_LEN_FRAME;
+    res = nvs_set_blob(handle, NVS_FLASH_KEY_CHUNK_3, (u1_t *)&LMIC.frame + MAX_LEN_FRAME, len3);
+    if (res != ESP_OK)
+        goto done;
+
+    res = nvs_set_u32(handle, NVS_FLASH_KEY_TIME, hal_esp32_get_time());
+    if (res != ESP_OK)
+        goto done;
+
+    res = nvs_commit(handle);
+    if (res != ESP_OK)
+        goto done;
+
+done:
+    nvs_close(handle);
+
+    if (res == ESP_ERR_NVS_NOT_INITIALIZED)
+    {
+        ESP_LOGW(TAG, "NVS storage is not initialized. Call 'nvs_flash_init()' first.");
+    }
+    else
+    {
+        ESP_ERROR_CHECK(res);
+    }
+}
+
+bool ttn_nvs_restore(int off_duration)
+{
+    nvs_handle handle = 0;
+    esp_err_t res = nvs_open(NVS_FLASH_PARTITION, NVS_READWRITE, &handle);
+    if (res != ESP_OK)
+        goto done;
+
+    uint32_t time_val;
+    res = nvs_get_u32(handle, NVS_FLASH_KEY_TIME, &time_val);
+    if (res != ESP_OK)
+        goto done;
+
+    size_t len1 = LMIC_DIST(radio, pendTxData);
+    res = nvs_get_blob(handle, NVS_FLASH_KEY_CHUNK_1, &LMIC.radio, &len1);
+    if (res != ESP_OK)
+        goto done;
+
+    size_t len2 = LMIC_DIST(pendTxData, frame) - MAX_LEN_PAYLOAD;
+    res = nvs_get_blob(handle, NVS_FLASH_KEY_CHUNK_2, (u1_t *)&LMIC.pendTxData + MAX_LEN_PAYLOAD, &len2);
+    if (res != ESP_OK)
+        goto done;
+
+    size_t len3 = sizeof(struct lmic_t) - LMIC_OFFSET(frame) - MAX_LEN_FRAME;
+    res = nvs_get_blob(handle, NVS_FLASH_KEY_CHUNK_3, (u1_t *)&LMIC.frame + MAX_LEN_FRAME, &len3);
+    if (res != ESP_OK)
+        goto done;
+
+    // invalidate data
+    res = nvs_erase_key(handle, NVS_FLASH_KEY_TIME);
+    if (res != ESP_OK)
+        goto done;
+
+    res = nvs_commit(handle);
+    if (res != ESP_OK)
+        goto done;
+
+    if (off_duration != 0)
+        hal_esp32_set_time(time_val + off_duration * 60);
+
+done:
+    nvs_close(handle);
+
+    if (res == ESP_ERR_NVS_NOT_INITIALIZED)
+    {
+        ESP_LOGW(TAG, "NVS storage is not initialized. Call 'nvs_flash_init()' first.");
+    }
+
+    return res == ESP_OK;
+}

src/ttn_nvs.h

@@ -0,0 +1,30 @@
+/*******************************************************************************
+ *
+ * ttn-esp32 - The Things Network device library for ESP-IDF / SX127x
+ *
+ * Copyright (c) 2018-2021 Manuel Bleichenbacher
+ *
+ * Licensed under MIT License
+ * https://opensource.org/licenses/MIT
+ *
+ * Functions for storing and retrieving TTN communication state from NVS.
+ *******************************************************************************/
+
+#ifndef TTN_NVS_H
+#define TTN_NVS_H
+
+#include <stdbool.h>
+
+#ifdef __cplusplus
+extern "C"
+{
+#endif
+
+    void ttn_nvs_save();
+    bool ttn_nvs_restore(int off_duration);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif